Marine geophysical surveys are often used for oil and gas exploration in marine environments. Various types of signal sources and sensors may be used in different types of geophysical surveys. For example, seismic surveys are based on the use of sound waves. In such a survey, a vessel may tow an acoustic source (e.g., an air gun or a marine vibrator) and a plurality of streamers along which a number of sound sensors (e.g., hydrophones or geophones) are located. Sound waves generated by the source may then be transmitted to the earth's crust and then reflected back and captured at the sensors. Sound waves received during a seismic survey may be analyzed to help locate hydrocarbon-bearing geological structures, and thus determine where deposits of oil and natural gas may be located. As another example, electromagnetic (EM) surveys may be conducted using EM signals transmitted by a submerged antenna and detected by EM receivers.
U.S. Patent Application Publication No. 2012/0257474 entitled “Method for Seismic Surveying using Wider Lateral Spacing between Sources to Improve Efficiency,” which is incorporated by reference herein, discloses some advantages of wide lateral spacing of towed signal sources.
This specification includes references to “one embodiment” or “an embodiment.” The appearances of the phrases “in one embodiment” or “in an embodiment” do not necessarily refer to the same embodiment. Particular features, structures, or characteristics may be combined in any suitable manner consistent with this disclosure.
Various units, circuits, or other components may be described or claimed as “configured to” perform a task or tasks. In such contexts, “configured to” is used to connote structure by indicating that the units/circuits/components include structure that performs the task or tasks during operation. As such, the unit/circuit/component can be said to be configured to perform the task even when the specified unit/circuit/component is not currently operational (e.g., is not on). The units/circuits/components used with the “configured to” language include hardware—for example, circuits, memory storing program instructions executable to implement the operation, etc. Reciting that a unit/circuit/component is “configured to” perform one or more tasks is expressly intended not to invoke 35 U.S.C. §112, sixth paragraph, for that unit/circuit/component.
As used herein, the term “based on” is used to describe one or more factors that affect a determination. This term does not foreclose additional factors that may affect a determination. That is, a determination may be solely based on those factors or based only in part on those factors. Consider the phrase “determine A based on B.” This phrase connotes that B is a factor that affects the determination of A, but does not foreclose the determination of A from also being based on C. In other instances, A may be determined based solely on B.